1. Field of the Invention
The invention pertains to the field of power transmission chains. More particularly, the invention pertains to an improvement in the structure of a chain for restraining chordal oscillation of a chain.
2. Description of Related Art
A power transmission chain for use in an automobile or motorcycle is generally constructed from multiple links that are connected endlessly by connecting pins inserted into pin apertures of the links. In operation of a power transmission chain, when the engagement frequency, determined by the number of teeth and the rotational speed of a sprocket around which a chain is wrapped, coincides with resonance frequency of a chain, determined by the length of a chain span and chain tension, resonance occurs in the chain span and the span oscillates severely in a lateral direction.
Various efforts have been made to prevent such resonant oscillation of a chain span. For example, FIGS. 4 and 5 of Japanese patent application laid-open publication No. 55-34580 show that two adjacent connecting pins of two adjacent links are coupled to each other via a leaf spring in order to decrease the engagement collision sound of a roller chain.
Japanese reference 55-34580 describes that the links articulate against the spring force of a leaf spring at the time of articulating motion of the adjacent links thereby restraining rapid articulation of the links at the engagement with the sprocket teeth to decrease the engagement collision sound. Also, in this case, chordal oscillation of a chain span may also be restrained due to restriction of articulating motion of the links.
However, in the prior art structure, since opposite end portions of the leaf spring need to be fixedly attached to the end portions of the connecting pins, the end portions of the connecting pins require caulking, thereby making the assembly work troublesome. Moreover, the width of a chain is increased by the width of a leaf spring. Also, in FIGS. 8 and 9 of Japanese reference 55-34580, a torsional coil spring is used to decrease the width of a chain. However, in this case, each connecting pin requires a torsional coil spring, thereby making the structure and the assembly work complicated and troublesome.
The present invention simplifies the structure for restraining chordal oscillation of a chain span of a power transmission chain and simplifies the assembly work of the chain.